Adaptation of a Diagnostic X-Ray Digital Flat Panel Detector for Treatment Verification of a Telecobalt Machine

Mark Pokoo-Aikins, Medical Physics Department, Graduate School of Nuclear and Allied Sciences, University of Ghana, P.O. Box AE 1, Accra-Ghana;Radiological and Medical Sciences Research Institute, Ghana Atomic Energy Commission, P.O. Box LG 80, Accra, Ghana.

Samuel Nii Tagoe, Medical Physics Department, Graduate School of Nuclear and Allied Sciences, University of Ghana, P.O. Box AE 1, Accra-Ghana; National Center for Radiotherapy and Nuclear Medicine Korle Bu Teaching Hospital, Accra, Ghana

Francis Hasford, Medical Physics Department, Graduate School of Nuclear and Allied Sciences, University of Ghana, P.O. Box AE 1, Accra-Ghana;Radiological and Medical Sciences Research Institute, Ghana Atomic Energy Commission, P.O. Box LG 80, Accra, Ghana.

Theresa Bebaaku Dery, Medical Physics Department, Graduate School of Nuclear and Allied Sciences, University of Ghana, P.O. Box AE 1, Accra-Ghana; Radiological and Medical Sciences Research Institute, Ghana Atomic Energy Commission, P.O. Box LG 80, Accra, Ghana.

John Boham Noonoo, University of Ghana Medical Center Radiology Department, P. O. Box LG 25, Accra, Ghana

Bismark Djan, Radiation Protection Institute Ghana Atomic Energy Commission, P. O. Box LG 80, Accra, Ghana

Abstract
Portal imaging devices, such as flat panel detectors (FPDs), have largely replaced traditional films in radiation therapy due to their ability to provide real-time imaging and digital storage. However, telecobalt machines are typically not equipped with such imaging systems, requiring the continued use of films for patient position verification. This reliance on film introduces cost implications and delays in treatment due to the time-consuming nature of film processing. This study explores the feasibility of adapting a diagnostic flat panel detector for portal imaging in a telecobalt machine. An in-house water phantom embedded with test objects was constructed to evaluate image quality. Image quality metrics, including signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and resolution using bar patterns, were assessed across various regions of interest. The detector software required predefined diagnostic X-ray exposure parameters, which could not be manually adjusted. Image quality was evaluated using various preset protocols, with analysis performed in ImageJ. Optimal image quality was achieved with the "Skull Lat" protocol (70 kVp, 8 mAs). However, for improved visualization of soft tissue, the "Right Clavicle AP" protocol (65 kVp, 16 mAs) is recommended. The findings demonstrate that a diagnostic flat panel detector can be effectively adapted for patient position verification in telecobalt treatments, enhancing treatment accuracy and patient safety.

Keywords
Patient Position Verification, Flat Panel Detector, Telecobalt Machine, Image Quality

Cite this paper
Victoria Nketia, Mark Pokoo-Aikins, Samuel Nii Tagoe, Francis Hasford, Theresa Bebaaku Dery, John Boham Noonoo, Bismark Djan, Adaptation of a Diagnostic X-Ray Digital Flat Panel Detector for Treatment Verification of a Telecobalt Machine , SCIREA Journal of Physics. Volume 10, Issue 4, August 2025 | PP. 159-175. 10.54647/physics140693

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